Heretofore the prior art has developed sealing adhesive compositions which serve to provide a peelable water vapor transmission resistant sealing structure. Such sealing closures should be characterized by a ready removal of the sealing gasket on which the sealing ply may be located, said removal being expressed in terms of peelability. At the same time, however, it is important that the structure have the requisite seal-tight integrity that comes with a ply of sealing gasketing material.
Closures for containers which are formed by activating a sealing film while it is in place intermediate a cap and the sealing face of a closure mouth have been practiced and indeed disclosed in prior art such as U.S. Pat. No. 2,620,939 to Weisgerber, Dec. 9, 1952. The practice set forth in such art is to heat the cap and general vicinity of the container closure mouth and cause the heat to be transferred through the cap thereby activating the sealing film intermediate the face of the closure mouth and a diaphram temporarily mounted within the cap structure. More recent advances in the art have taught the use of induction heat sealing to cause a fusion between the sealing composition or resin located on the membrane and the sealing face of the closure mouth, to wit, U.S. Pat. No. 2,937,481 to Palmer, May 24, 1964, Method of Producing a Package. The Palmer Patent in essence achieves a fusion of the sealing composition per se with the sealing face of the closure. In effecting this fusion, however, there is remaining great difficulty in peelability and in essence there is a need for destruction of the membrane which is not always faithfully achieved, thus detracting from consumer acceptability of many consumer-oriented products.